The story is set "slightly in the future" and revolves around Aya "Aachan" Okamura, a woman who has been working for two years and has begun living on her own for a job opportunity. With Aachan's mother working overseas as a doctor, Aachan's father is now living alone with the family's longtime pet cat Mii-san. One night, Aachan returns from a long day at work, and as she rests on her bed, she reminiscences about the times the family had together. She remembers the sadness she felt when her mom went overseas, and the solace she felt when her father brought home Mii-san to give her comfort. Then, she receives a phone call…
A parasitic alien soul is injected into the body of Melanie Stryder. Instead of carrying out her race's mission of taking over the Earth, "Wanda" (as she comes to be called) forms a bond with her host and sets out to aid other free humans.
Life for former United Nations investigator Gerry Lane and his family seems content. Suddenly, the world is plagued by a mysterious infection turning whole human populations into rampaging mindless zombies.
Ray Breslin is the world's foremost authority on structural security. After analyzing every high security prison and learning a vast array of survival skills so he can design escape-proof prisons, his skills are put to the test.
Virgil Oldman is a world renowned antiques expert and auctioneer. An eccentric genius, he leads a solitary life, going to extreme lengths to keep his distance from the messiness of human relationships.